Crontab Time Values
There are five fields at the beginning of each crontab entry. Each field represents a specific time and/or day. Starting from left to right they are:
1. Minute [0,59]
2. Hour [0,23]
3. Day of the month [1,31]
4. Month of the year [1,12]
5. Day of the week ([0,6] with 0=Sunday)
Valid entries can be an asterisk [...]